The present invention relates to a color cathode ray tube, and particularly to an improved self-compensating hook spring of a shadow mask frame assembly.
Generally, a color cathode ray tube includes a shadow mask as a color selecting grid in order that an electron beam emitted from an electron gun accurately lands on a dotted or stripped phosphor layer. As illustrated in FIG. 1, a multitude of electrode beam passing holes 6' are formed in the body of shadow mask 6 whose edge is supported by a rectangular frame 5. A shadow mask frame assembly formed by fixing shadow mask 6 to frame 5 is suspended in the inner space of a panel 3 by means of a self-compensating hook spring provided on the side of frame 5 which is supported by stud pins 4 on the inside of a panel skirt 3a.
As illustrated in FIG. 2, when frame 5 faces and is substantially parallel to the inside surface of panel skirt 3a, the shadow mask frame assembly is positioned in the internal space of panel 3 such that one end of a hook spring 10 is welded to one side of frame 5. The other end of the hook spring is formed to allow stud pin 4 which is embedded in the inner side of panel skirt 3a to be inserted thereinto.
A conventional hook spring 10 is composed of a fixed planar part 11 welded to the side of frame 5, a coupling part 13 having a hole 13a into which stud pin 4 is hooked, and substantially parallel with fixed planar part 11, and an angular connecting part 12 for connecting fixed planar part 11 with coupling part 13. The angle formed between fixed planar part 11 and connecting part 12 is generally 40-50 degrees.
The conventional cathode ray tube formed as the above has a problem that hook spring 10 is too severely and elastically strained to stably suspend the shadow mask frame assembly. Here, hook spring 10 including fixed planar part 11 and connecting part 12 is bent by b 40-50 degrees as described above. By this construction, a local plastic deformation occurs while bending the spring of a highly resilient material. Therefore, the resilience at the bending portion is less flexible than at other portions, so that proper resilience, which is required for stably suspending the shadow mask frame assembly to the internal space of panel, is not achieved.
In order to solve aforesaid problems, a method has been suggested wherein the fixed planar part and connecting part are separately manufactured and then welded together. However, this method increases the production time for manufacturing the hook spring, and thus is unfavorable to the productivity of the final product.